Here's a link to some info I found, HTH :

Here is a link that might be useful: Garlic Mustard

Thanks. I'd seen that in all the other posts, and I'm familiar with the weed. What I was looking for was some actual, "what worked" kind of response. Does anyone have any experience to share?

Since it sounds like you have a large infestation, I might suggest using a scythe or cordless weed-whacker to repeatedly maul the first-year plants (I assume you already know it's a biennial and needs to reseed itself to keep going). If you do that several times during the growing-season, logic dictates that you will lessen the number of viable seeds created next year. Do not, of course, do this to plants that have already flowered; they must be cut or pulled and bagged for the trash.

My understanding is the seed bank lasts about five years, so it looks like you may have found yourself a new hobby. I sympathize; we are currently battling garlic mustard and Japanese knotweed and a major mugwort infestation, all on a quarter-acre city lot. Phooey.

Well, I spent the day pulling up 3' tall weeds by the root and herbiciding all the mini-sprouts in the woods. We'll see how much of that last part was effective. The place certainly looks better with all those weeds gone, but I know there's so many more just waiting to grow, so I guess you're right - I have a new hobby! Ugh. I think these larger ones are in their third year, so you can imagine the vast number of seedlings. And they are everywhere in my neighborhood/town. I dug and killed as much as possible near my lawn (borders woods) and put down mulch - must buy more! But the woods are not really controllable - just trying to manage down the things. Anyway, thanks for the input!

The key to garlic mustard is to prevent more seed from making it to the ground. It takes years. Work from the least infested to the most infested areas. It's a challenge.

Here is a link that might be useful: Garlic Mustard

Pulling works. I have been pulling GM on my acre for the last three years. Its takes a couple years, but it numbers are significantly reduced, every year...

If it's started flowering, don't leave them lying around-they will still go to seed (so I've been told).

Look into burning if it is a viable option (oak woodland can be managed that way).

I know a woman who turned acres of honeysuckle and GM into a gorgeous woodland setting single-handedly, and she was in her seventies. Took her a while, though!

I was on a mission to control wood nettles when I found a large patch of something with a white flower that had totally crowded out the nettles. I was so happy until I researched it. I had such a heavy invasion by the time I found it that I first tried pulling..then went to roundup. I also tried putting a pre emergent down in case killing the tall plants gave light to seeds that hadn't germinated. Diligence and roundup seem the only way. I got grief because roundup would kill everything under it, but what people didn't know was the GM had already done that. It seems to be moved by deer because new patches appear along their paths. Since both my neighbors have it and don't seem to care, I am constantly battling it. The only good thing about it is that makes me walk my woods weekly if the mosquitos aren't too bad, so I see more of the natives which I have new appreciation for.